clk: keystone: fix a trivial typo

s/regsiter/register/

Signed-off-by: Geliang Tang <geliangtang@163.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

drivers/clk/keystone/pll.c

@@ -157,7 +157,7 @@ out:
  * _of_clk_init - PLL initialisation via DT
  * @node: device tree node for this clock
  * @pllctrl: If true, lower 6 bits of multiplier is in pllm register of
- *		pll controller, else it is in the control regsiter0(bit 11-6)
+ *		pll controller, else it is in the control register0(bit 11-6)
  */
 static void __init _of_pll_clk_init(struct device_node *node, bool pllctrl)
 {